Basket strainer-stopper assemblies to control the flow of water from sink drains are well known.
The most widely used form of strainer-stopper assemblies have a basket strainer, a control handle and a stopper which is positioned below the strainer and attached to the control handle. The control handle and stopper move independently of the basket strainer. This type of assembly normally requires the alignment and registration of the stopper or the control handle with the drain outlet or with the strainer basket to hold the stopper in an open drain position or retain it in a closed drain position. Usually the alignment or registration of the components must be accomplished in a concealed space out of the sight of the user. As a result, the user often juggles or moves the control handle or the entire unit from one position to another before proper alignment or registration is made.
Another type of strainer-stopper assembly in use has the strainer basket, the control handle and the stopper attached together to form a single unit. The control handle and stopper do not move independent of the strainer basket. In use, the entire assembly is moved from a raised open position which permits water to flow to the sink drain to a lower closed position in which the stopper forms a seal with the drain opening to prevent the escape of water. A distinct advantage of this type of assembly is that the user can see from the position of the assembly if the drain is open or closed. Such an assembly requires a stable means of supporting the entire assembly in the open position against the forces of gravity and the head of water in the sink which tend to move it to the closed position. However, most such support means are unduly complex, difficult to clean and/or fail to provide stable support for the assembly in the open position.